Question

Why does a lump cotton wool shrink in the water?

Answer 1

Hint: The concept which is involved in this question is that of the air trapped inside the lump of cotton wool. Also, this question can be understood by the hyper concentration and hypo concentration concept.First, we need to thoroughly understand what is hyper concentration and hypo concentration. These two terms are studied in a bio stream where the shrinking and swelling of the cells is an important phenomenon to understand.

Complete step by step answer:
When a cell is introduced in a hyper-concentrated solution, That is, the solution contains more solute particles. Therefore the water will move from its higher concentration to lower concentration, that is from cell to solution and will result in the shrinking of the cell.
When a cell is introduced in a hypo concentrated solution, that is, the solution contains fewer solute particles. The water will move from its higher concentration to the lower concentration, that is from the solution to the cell and will result in swelling of the cell.
The same happens when a cotton lump is introduced in water. That is a deficiency of water in the cotton lump and there is air trapped inside it when it is introduced in the water. The water molecule will move from its higher concentration to its lower concentration, that is from the water to the cotton lump and therefore the cotton Lump gets shrunk. It is opposite from the cell because there is trapped air inside the cotton lump which releases. Resulting in the shrinking of the cotton lump.

Note:
The thing you need to remember is in hyper concentration the cell gets shrink cause the water to move from the cell to the solution. In hyper concentration, the cell gets swelled because the water moves from the solution to the cell.